Metropoulos Forum

Separate thread time. Here is a revised idea: this will handle just about anything!


You have dual primaries that can be hooked up in a number of ways 240, 230, 120, 115, etc... The heater voltage has been scaled to give a better margin with a lighter load. the secondary still has the option for 330VAC so you don't tax the screens of EL34, 6L6, 5881 tube types, and also has a higher 375V tap for big Kinkless bottles. I got rid of the CT so the window can be better utilized for thicker wire (beefed up current rating), and help with a smaller footprint. the 900ma rating suggests the most worse case scenario a quartet of KT88's might pull from the supply under wide open peak conditions, and may not reflect how the company rates the tap.

Separate bias tap, and 18VAC tap for Switching, DC heaters, OPAMP, and CMOS circuitry

Discuss

Were do I sign up. and did you get my 5150 volt readings?

Is this PT to be used with a full wave bridge rectifier on 50W and 100W amps?

Brian Wallace wrote:Is this PT to be used with a full wave bridge rectifier on 50W and 100W amps?

The Design is for 100W, but could be used for 50W too

Hey Joey,

wow, 900mA HT- a real monster!

But: because the weight and cost of such an overkill weapon I personally would vote for:

- 500mA (DC)
- a 16 Volt tap on the 18 Volt winding (less heat dissipation for the stabilizer when used for 12,6 Volt DC heaters)

@Brian & Larry: what do you both think about such an universal transformer as highly experienced manufacturers/ amp builders?

Regards

Robert

But: because the weight and cost of such an overkill weapon I personally would vote for:

- 500mA (DC)

from second Merlin blancowe book about designing power supplies , page 54, we have an exemple :

an amplifier with supply voltage of 400Vdc at max current of 500mA (looks like a 100w marshall at full power)
full wave rectifier, 60hz, 10% ripple voltage

his result is a transformer rated at 310 Vrms (with 13 % regulation) at 850 mA

So for me 900ma looks right

Hi nico,

e.g.: the HT winding on the HAMMOND 290HX (= Hammond Guitar series for JCM800 / JMP 100 Watt) is rated for (RMS) 356V @ 420 mA.

Since Hammond IMO is very accurate/conservative/serious about their transformer specs, I believe that their values are authentic for a 100 Watter (historically correct).

Regards

Robert

robert wrote:Hey Joey,

wow, 900mA HT- a real monster!

But: because the weight and cost of such an overkill weapon I personally would vote for:

- 500mA (DC)

yeah....... I'm thinking of bringing it down to FWB@500-560ma

robert wrote: a 16 Volt tap on the 18 Volt winding (less heat dissipation for the stabilizer when used for 12,6 Volt DC heaters)

I thought about excess dissipation for the regulator too, and picked 18 because it was a good compromise between 12.6VDC for the regulated heaters, and high enough dual rail voltage for IC's I can just bring it down to 16.

+1, I also think that 500mA or 560 mA RMS HT is fairly enough.

BTW: this will help a bit to keep the costs down

But now it's time IMO that "Magnetic Components" will chime in again

Regards

Robert

robert wrote:+1, I also think that 500mA or 560 mA RMS HT is fairly enough.

BTW: this will help a bit to keep the costs down

But now it's time IMO that "Magnetic Components" will chime in again

Regards

Robert

Robert,

I'm going to send the specs to Joe, and see what he says. If he declines the opportunity, I have another lead from an American Manufacturer that may produce it for an affordable price.

Joey,

great!

BTW: with the HT bridge rectification circuit, we can realize the "HI HT / LO HT / virtual variac option" with a much easier to get DPTT "on/off/on" switch (instead of this much harder to get "TPTT" switch, which must be used in a 2- way HT rectification circuit).

Regards

Robert

Joey,

Do you mean 900 AC in the schematic above?

Please advise.

Joe Janisch
ClassicTone By Magnetic Components, Inc.

ClassicTone wrote:Joey,

Do you mean 900 AC in the schematic above?

Please advise.

Joe Janisch
ClassicTone By Magnetic Components, Inc.

No, It is going to be 500ma, I'll send you the revised drawing here in a bit. 900ma is wayyyy to much, and the thing would be enormous.

Joey,

Yes, that would be huge. 500 is much better. It will still be a bit larger than the 40-18024 depending on the final specs you all want to see in this part. I hope that is okay with everyone here.

I'll await your drawing then.

F.Y.I. I will probably announce a project amplifier transformer category to our Classictone line specifically for you hardcore DIY guys and this will probably be the first item.

Joe Janisch
ClassicTone By Magnetic Components, Inc.
http://www.classictone.net" onclick="window.open(this.href);return false;

Okay, here is hopefully a final mark up:


The only thing people so far have had concerns with is the HT secondary rating, and how the rating is actually done by the manufacturer. so what ever the means, or number the secondary needs to support a possible 500Ma DC load with FWB rectification. So discuss

EDIT: would you guys rather have dual primaries, or a just a tapped primary